Enhanced Encapsulation of Actives in Self-Sealing Microcapsules by Precipitation in Capsule Shells

Microcapsules with core-shell structures are excellent vehicles for the encapsulation of active ingredients; however, the actives often leak out of these structures over time, without observable damage to them. We present a novel approach to enhancing the encapsulation of active ingredients inside microcapsules. We use two components that can form solid precipitates upon mixing and add one each to the microcapsule core and to the continuous phase. The components diffuse through the shell in the same manner as the actives, but upon meeting, they precipitate to form solid particles within the shell; this significantly reduces leakage through the shell of the microcapsules. We show that the reduction in the leakage of actives is due to the blockage of channels or pores that exist in the shell of the capsules by the solid precipitates.